I took a university course on Unix internals in 1988. The lecturer started by announcing "this is the last year that we will teach this course as Unix is now very out of date and is being left further behind every year". It turned out to be the best course I ever took.
I remember a course I took once with the venerable Peter Denning, the hardest professor I ever had and the proudest I've ever been from a grade I received...he was giving a lecture on processes in Operating Systems and one of the students raised his hand over some minor point:
"I don't think that's correct"
"what's not correct?"
"<whatever the minor point was> I've run ps on my linux laptop and it contradicts what you are saying"
"#1, I said no computers during the lectures for this course, #2 I am in fact correct because I invented it, now either close your laptop and pay attention or get out of my class."
Now, many years later, I'm constantly surprised at how pertinent and immediate what I learned in that class constantly is and how it keeps unfolding in my mind. The kind of simple, composable concepts he lectured us on have penetrated almost all of my work since then. It's amazing what robust ideas our forefathers invented from whole-cloth!
He sounds like an arrogant dick. The fact that he invented something doesn't mean it works the same way on every OS... I've worked with a few academics and unfortunately this attitude seems rather common.
This was many years ago, so it's a bit hazy, It was something to do with process ID assignment of some root process by the OS.
It's hard to explain, but he didn't come off as arrogant. He was one of those rare legitimate experts who had a hand in the formation of things we take for granted today, knew it, and didn't take kindly to young whipper-snapper know-it-alls with their Linux laptops open and not paying attention during class challenging him on his accomplishments.
He's one of the fathers of the modern notion of the field of "computer science", before that it was EE, or Math, or some other field. His PhD thesis introduced core multi-process OS concepts used in every Operating System since then and basically invented the modern theory behind Virtual Memory.
He helped design Multics which was worked on by Thompson and Ritchie which was the template for their sequel project Unix, he co-founded CSNET which was the academic Computer Science network that's one of those networks in the "inter" part of the word "Internet" -- it was also the network that hosted one of the first experiments in free software distribution (and is still around "netlib").
Challenging him on these kinds of issues is like challenging Neil Armstrong or Buzz Aldrin on actually landing on the moon.
He worked insane hours, put an incredible amount of time and effort into education (something more professors could learn from), had a very well structured course that had been refined down to near perfection and always went out of his way to make time for students. I remember many meetings with him where he was absolutely exhausted looking, but he never rushed us out of his office.
He was very insistent that you put as much effort into his class as he did, and anything less was disrespectful. And that's how he ran it.
He was easily the best professor I had in all of my education, full-stop.
